1. Field of the Invention
This invention relates to efficient, safe and comfortable vehicles for daily personal transportation, and particularly, to a center tracking vehicle with retractable support side wheels to prevent turning over during normal use and during collision.
2. Description of the Prior Art
Two wheeled, or center track, vehicles, such as bicycles and motorcycles have long been commercially used to achieve the above mentioned objectives, however, it is obvious that they do not offer the level of comfort and protection, both from weather and during a collision, acceptable to the general public in developed countries. Furthermore, touring motorcycles do not offer a significant improvement in gas mileage in comparison to economy sized automobiles, because of their lack of aerodynamic efficiency imposed by the fully exposed body of the rider.
Full bodied center tracking vehicles have been described in various patents. These vehicles require means for stabilization against falling over when stopped, moving at low speeds, or when moving on wet or otherwise slippery roadways.
One prior art technique of stabilizing single track vehicles is to use a large passive gyro and utilize its precessional moment to control body roll. In U.S. Pat. No. 3,465,840 to Summers, the vehicle is stabilized against rolling over by a large brute force gyro having a lateral spin axis and a vertical gimbal axis. Roll equilibrium is maintained by application of a vehicle righting gimbal force as a function of gimbal precession rate. While the method disclosed in Summers has met with some success in stabilizing large ships, the weight, expense and complexity of this method have barred two wheeled vehicles from using the method in an economical manner. A second type of stabilizing method which has been described in previous patents uses retractable outrigger wheels of various designs and mechanisms. U.S. Pat. No. 3,700,059 to Sutton discloses a vehicle stabilizing system wherein the outrigger wheels can be steered in the direction of travel, rotated to meet road speed and raised or lowered through an electric mechanized system. Drawbacks to this design involve its great mechanical complexity thus increasing manufacturing cost, its completely exposed outrigger wheel mechanism along both sides of the vehicle, thus taking up almost as much road space as a conventional automobile and offering no advantage in term of space saving ability, and furthermore, the fully exposed outrigger mechanism creates a large amount of wind drag thus offering little advantage in fuel economy over that of an economy car. In U.S. Pat. No. 4,513,837 to Archer, the outrigger device is completely retractable upward in the vehicle's body. However, this upward retractable mechanism can only permit a narrow outrigger support track which makes the vehicle vulnerable to rolling over in slippery road conditions or at a high banking angle. Once the vehicle is rolled over on its side, there is no mechanism built in that can immediately right it, thus creating a very vulnerable situation where it can be run over by other cars. Furthermore, Archer's outrigger mechanism is not placed in the same plane with the center of gravity of the vehicle where it would exert the most effect, but instead is placed behind the center of gravity in line with the rear drive wheel, where it would have decreased stabilizing effect. In U.S. Pat. No. 4,691,798 to Engelbach, the outrigger mechanism is attached to the vehicle frame where it pivots upward when retracted and downward when deployed, and those described actions are coupled to an automatic system controlled by a microprocessor guided by a rate gyro sensor. While no mechanical details regarding the construction of such an outrigger mechanism was described in this patent, it is clear that an outrigger system of sufficient track width for satisfactory stabilization when pivoting up or down on both sides of the vehicle can interfere with traffic on either side of the vehicle, therefore limiting this vehicle's utility. And, like the previously described invention, this design's outrigger system is also placed in line with the rear wheel of the vehicle, thereby limiting its stabilizing ability. In U.S. Pat. No. 4,133,402, a simple and practical outrigger assembly of narrow track base is described attached to the rear wheel of the vehicle, and therefore, as in the two previous patents, its stabilizing ability is limited. In U.S. Pat. No. 5,048,864 to Geiger, a similar outrigger system was described which was very much similar to that of Archer's in that the outrigger system is placed in line with the rear wheel and not near the center of gravity of the vehicle thus significantly limiting its stabilizing ability. Furthermore, this patent requires the width of the vehicle to be nearly as much as that of a sub-compact size car for adequate stability and hence offers little advantage in term of road saving ability.